1. Field of the Invention
This invention relates to corrosion inhibited antifreeze/coolant concentrate formulations, and to aqueous antifreeze/coolant compositions for use in the cooling systems of internal combustion engines. More particularly, this invention relates to a corrosion-inhibited water soluble liquid alcohol antifreeze/coolant concentrate formulation comprising monobasic and dibasic acids and/or the alkali metal, ammonium, or amine salts of said acids, a hydrocarbyl azole, and a hydrocarbyl alkali metal sulfonate, and to aqueous antifreeze/coolant compositions containing the same.
Automobile engine cooling systems contain a variety of metals, including copper, solder, brass, steel, cast iron, aluminum, magnesium, and their alloys. The possibility of corrosive attack on such metals is high, due to the presence of various ions as well as the high temperatures, pressures, and flow rates found in such cooling systems. The presence of corrosion products within the cooling system can interfere with heat transfer from the engine combustion chambers, which may subsequently cause engine overheating and engine component failure due to excess metal temperatures. See generally Fay, R. H., "Antifreezes and Deicing Fluids," In: Kirk-Othmer Encyclopedia of Chemical Technology (1978 ed.), vol. 3, pp. 79-95. It would therefore be generally advantageous if the formation of corrosion products within automobile cooling systems could be controlled or eliminated. It is one object of the instant invention to provide a corrosion inhibited antifreeze/coolant useful in the prevention and control of corrosion in automobile engine cooling systems containing various metals.
The trend towards improved fuel economy for automobiles has led to the increased use of aluminum and in some cases magnesium for engine and cooling system components. However, it has been found that pitting and crevice corrosion are particularly prevalent in aluminum-containing cooling systems. Many conventional corrosion inhibitor additives used in automobile cooling systems do not provide adequate protection against the pitting and crevice corrosion phenomena found with various aluminum and magnesium alloys. It would therefore be particularly advantageous if the pitting and crevice corrosion phenomena found in automobile cooling systems containing aluminum or magnesium alloys could be controlled or eliminated. It is another object of the instant invention to provide a corrosion inhibited antifreeze/coolant for use in automobile cooling systems which prevents or controls pitting and crevice corrosion of aluminum and magnesium meal surfaces.
All corrosion inhibitors employed in automobile antifreeze/coolant formulations are gradually depleted by use and the build-up of corrosion products in the cooling system. It would thus be advantageous if the build-up of corrosion products within the system and subsequent corrosion inhibitor depletion or degradation could be controlled or eliminated. It is a further object of the instant invention to provide a corrosion inhibited antifreeze/coolant which is less prone to depletion or degradation than traditional corrosion inhibited antifreeze/coolant formulations.
2. Information Disclosure Statement
It is well known that various monobasic and dibasic acids as well as the salts of such acids are effective as corrosion inhibitors when employed in antifreeze/coolant formulations. For example, co-assigned U.S. Pat. Appl. Ser. No. 813,902, filed on Dec. 27, 1985 (incorporated herein by reference) describes various U.S. and foreign references which disclose the use of basic acids/salts as corrosion inhibitors in antifreeze/coolant formulations, and also discloses a corrosion inhibitor which comprises the combination of a C.sub.5 -C.sub.16 aliphatic monobasic acid/salt, a C.sub.5 -C.sub.16 hydrocarbyl dibasic acid/salt, and a hydrocarbyl triazole for use in engine antifreeze/coolant systems.
Various references also describe the use of sulfonic acid/sulfonate compounds as corrosion inhibitors. For example:
U.S. Pat. No. 4,528,108 describes an oleaginous coolant fluid composition comprising, as one component thereof, a basic metal salt of an organic acid such as sodium overbased alkyl benzene sulfonate;
Co-assigned U.S. Pat. No. 3,264,218 describes a corrosion-inhibited antifreeze composition comprising, as one component thereof, between 0.5-5.0 wt.% of a CO.sub.2 neutralized basic alkaline earth metal hydrocarbon sulfonate having a molecular weight between about 900-1500;
U.S. Pat. No. 2,225,866 discloses a corrosion inhibited antifreeze composition comprising an alcohol, 1.0-3.0 wt.% of a mineral oil distillate, 1.0-5.0 wt.% water, 0.1-0.5 wt.% borax, 0.05-0.2 wt.% soap, 0.001 wt.% dye, 0.08-0.3 wt.% of an oil-soluble sulfonate, and sufficient alkali to give a pH of at least 9.5 to a 40% solution of said antifreeze composition in water;
Marshall, A. "Effective Inhibition for Cooling Systems," Water Serv. (London), Vol. 88 (1984), pp. 148-149 teaches the use of a sulfonated polymer in circulating water systems;
Eur. Pat. Appl. No. 093,508 describes the use of a maleic anhydride/styrene sulfonate copolymer in combination with other corrosion inhibitors in aqueous systems;
PCT Int. Appl. WO 8,302,628 describes the use of a composition for inhibiting the corrosion of iron based metals in contact with aqueous systems, where said composition comprises a water soluble organic phosphate and a sulfonic acid copolymer with a molecular weight range of 1,000-10,000;
CA Abstract, vol. 96, paragraph 13050y, p.440 (1982) teaches the use of sodium dialkylphenyl sulfonates as corrosion inhibitors in the cooling systems of internal combustion engines; and
CA Abstract, vol. 99, paragraph 200334t (1983) describes the use of sodium alpha-olefin sulfonates in cleansers, shampoos, and detergents.